Hearing instruments of any kind have over the later years been increasingly able to communicate with the surroundings, including communicating with remote controls, spouse microphones, other hearing instruments and lately also directly with smart phones and other external electronic devices.
Hearing instruments are very small and delicate devices and to fulfil the above requirements, the hearing instruments need to comprise many electronic and metallic components contained in a housing small enough to fit in the ear canal of a human or behind the outer ear. The many electronic and metallic components in combination with the small size of the hearing instrument housing impose high design constraints on any antennas to be used in hearing instruments with wireless communication capabilities.
Radio frequency antennas have been used in hearing instruments to achieve connectivity with a wide range of devices. However, also magnetic induction antennas are being used in hearing instruments. Hearing instruments are supplied with power from hearing instrument batteries, having a limited power supply, and for the users, longer lifetime or longer time-between-charging for such hearing instrument batteries is expected, even when the capabilities of the hearing instruments are improved. The hearing instrument comprises a number of electronic components, which are all supplied with power from the battery. Thus, optimization of power usage is a concern for all electronic components in the hearing instrument, and particular wireless communication may consume significant power. Therefore, for antennas in hearing instruments in general, there is a need to ensure that the antennas and the communication protocols are designed to reduce the power consumption while maintaining a high efficiency.
In some scenarios, magnetic induction antennas may be preferred due to e.g. increased efficiency, minimized absorption by the head, etc. However, there is a need to optimize power consumption for driving magnetic induction antennas.